The effects of physical stress on the human body can be assessed by measuring anaerobic threshold and oxygen consumption rates during exercise. For example, both professional and non-professional athletes may attempt to quantitatively assess the effectiveness of a training regimen by measuring these parameters during periods of incremental physical exercise. Effective athletic training regimens typically increase both anaerobic thresholds and oxygen consumption rates.
The rate of oxygen consumption in human tissue can be measured by a trained operator with complex and expensive gas analysis equipment. Typically, these measurements are performed in a laboratory. In contrast, an anaerobic threshold can be determined in the field, but typically involves multiple invasive measurements (e.g., multiple blood withdrawals, typically via a finger stick to obtain a drop of blood). As a result, measuring an anaerobic threshold can be both time-consuming and uncomfortable for the subject.